1. Field of the Invention
This invention relates to improvements in a bearing, in particular to an expansion compensating bearing. The expansion compensating bearing is a bearing which comprises an inner race and an outer race disposed concentrically, rolling members interposed between the two races, and synthetic resin rings mounted on the outer race. The outer race is held through the resin rings by a housing (for example, made of aluminum) greater in coefficient of linear expansion than the outer race so that even if heat is applied to the housing to expand it, the variation in the relation of fit between the housing and the outer race is minimized (the outer race is prevented from rotating relative to the housing).
2. Related Background Art
Various expansion compensating bearings of this type have therefore been proposed and some of them have been put into practical use. For example, Japanese Utility Model Publication No. 53873/1982 discloses a structure in which synthetic resin is injection-molded in a belt-like form so as to protrude from the outer peripheral surface of the outer race of the bearing by a predetermined dimension. The resin is molded in two concave circumferential grooves juxtaposed axially in the outer peripheral surface of the outer race which provides a fitting surface relative to a housing. In this prior art, particularly the axially outer corner of the bottom of each of the concave circumferential grooves is formed into a wedge shape, and the bottom of the wedge-shaped portion is made into a curved surface. The axially inner corner is also curved, but has no wedge shape, and its radius is made greater than the radius of the curved surface.
In the above-described conventional circumferential groove configuration, the wedge-shaped portion is formed at the corner of the groove bottom and therefore, the reaction against the turn-up during incorporation is small. Also the groove bottom has corners and thus, the strength of the outer race may not always be sufficient. Also, there has been a disadvantage in that the cutting tool for working the circumferential grooves, particularly the cutting edge portion for working the wedge portion, is liable to be damaged.